Glow cathode indicator tube having memory



April 18, 1967 T. c. MALONEY 3,315,115

GLOW CATHODE INDICATOR TUBE HAVING MEMORY Filed July 8, 1964 IN V EN TOR.

Tnoa'g gs C. MA LONE) madam A TTOPNE Y United States Patent 3,315,115 GLOW CATHODE INDICATOR TUBE HAVING MEMORY Thomas C. Maloney, Bernardsville, N.J., assignor to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed July 8, 1964, Ser. No. 381,112

6 Claims. (Cl. 313-410) This invention relates to glow tubes.

' One of the most popular and widely used glow cathode indicator tubes includes a gas-filled envelope which contains an anode electrode and a stack of glow cathode electrodes which are in the form of characters or which may be combined to represent characters. A tube of this type is described in United States Patent 2,990,061 and is sold commercially as tube type 6844A. Tubes of this type have been accepted by industry and are used extensively and, for the most part, they have only one disadvantage; they do not have memory. Memory is the ability of the tube to continue to display a character after the applied signal which initiated the display is removed.

Accordingly, the principles and objects of the present invention concern the provision of a glow cathode indicator tube which has memory.

Briefly, a tube embodying the invention includes a gasfilled envelope which contains an anode and a plurality of glow cathode electrodes. An electrode assembly for incorporating memory for the glow cathodes is provided and includes a separate three-electrode gas cell coupled to each glow cathode. In operation of the invention, suitable bias voltages are applied and a signal pulse, for operating a particular glow cathode, is applied to the appropriate gas cell. The gas cell thus energized turns on and holds on the proper glow cathode after the input or energizing signal pulse is removed.

The invention is described in greater detail below with reference to the drawing wherein the single figure is a perspective view, partly in section, of a tube embodying the invention.

The present invention is particularly adapted for use with a multiple glow cathode indicator tube, such as the type 6844A tube, and, for convenience, this type of tube is illustrated and described. However, the applicability of the principles of the invention to other types of devices will be clear to those skilled in the art.

An indicator tube 10 embodying the principles of the invention includes a glass envelope 14 filled with a gas such as neon, argon, or the like for supporting cathode glow. The envelope includes a base or stem 16. In cathode glow a narrow sheath of gas, surrounding a cathode, glows and the cathode itself appears to glow. The envelope 14 contains a stack of cathode glow indicator electrodes 18, usually ten in number, each representing a particular character. For convenience, fewer than ten cathode indicator electrodes are shown in the drawing. The cathodes are mounted insulated from each other on two suitably insulated posts 22 and 24 inside a metal cup 28 which comprises the anode electrode for the glow cathodes 18. The cup 28 is provided with suitable Vertical slots through which leads 32 from the cathodes extend to pins 34, by means of which energizing potentials are applied. One pin 34' is used for applying operating potentials to the anode cup 28 and is thus connected to the anode cup by a lead 32'. Since a type 6844A tube is well known, all of the intimate structural features thereof need not be shown and described in any more detail than as above.

According to the invention, a separate memory cell 38 is provided for each indicator cathode 18, with all of the memory cells being isolated from each other in a suitable cathode gaseous indicator housing 40, preferably of insulating material such as glass, ceramic, or the like. The housing 40 may be made of a plurality of sections suitably sealed together according to known techniques. The cells 38 may be disposed in a circular array in the housing 40, or they may be disposed in any suitable manner which permits of easy construction. For purposes of illustration, three cells 38 are shown, although a sectional view might not ordinarily intersect three cells if the cells were disposed in a circular array. In the housing 40, the chamber provided for each memory cell is generally cylindrical and includes an enlarged central region 42 and two smaller diameter upper and lower end regions 43 and 44, respectively. Each memory cell 38 includes a first cylindrical electrode 50, known as the memory cathode, positioned in the large-diameter central portion of the chamber of the cell. Each of these first memory cathode electrodes 50 is dimensioned to form a relatively tight fit in the chamber, or it is secured in place by a firing operation, or the like, which is well known in the art. The memory cathodes 50 are connected together by a common lead 51 which is supported in a suitable annular notch in housing 40, and a pin 52 is provided extending through the stem of the envelope 14 in housing 40 to make contact with lead 51.

The pins 34 which are coupled to indicator cathodes 18 are used as memory anodes in the memory cells 38. Each anode pin 34 extends into the upper smaller diameter portion of the memory cell chamber to a slight extent. It does not extend into the large-diameter portion of the chamber.

Each memory cell 38 also includes a trigger electrode 54 which extends from outside the envelope, as an external tube contact pin, through the tube stem 16 and into the lower narrow portion of the cell chamber. The inner end of each trigger electrode lies closer to its associated cathode 50 than the associated memory anode 34.

In operation of the tube 10, anode potential of about 300 volts, is applied through pin 34 to the anode cup 28, and ground potential is applied to all of the memory cathodes 50 through pin 52. When it is desired to cause one of the indicator cathodes to glow, a switching potential of about volts is applied to the appropriate trigger electrode 54. Initially, there is a discharge between the selected trigger 54 and the associated memory cathode 50, and this discharge transfers to the path between the anode cup 28 and the glow cathode 18 associated with the energized trigger electrode. The glow cathode is thus caused to glow and remains glowing after the initial energizing signal is removed from the trigger electrode 54.

What is claimed is:

1. A cold cathode gaseous glow tube comprising a gas-filled envelope,

an anode electrode,

a plurality of glow cathode electrodes within said envelope in operative relation with said anode,

and a multiple electrode gas-filled memory cell coupled to each glow cathode electrode inside said envelope.

2. The tube defined in claim 1 wherein each memory cell includes a memory cathode, a memory anode, and a memory trigger electrode, each memory anode electrode of a memory cell being connected to a glow cathode electrode.

3. The tube defined in claim 1 wherein the memory cells are vertically oriented glow cathode electrodes,

each memory cell including a memory cathode, a memory anode, and a memory trigger electrode, each memory anode electrode being connected to a glow cathode electrode and spaced farther from its associated memory cathode than the associated memory trigger electrode.

4. The tube defined in claim 1 and including beneath said an insulating housing for said memory cells, each cell being formed in a separate chamber in said housing,

the memory cells being vertically oriented beneath said glow cathode electrodes,

each memory 'cell including a memory cathode located at about the center of a chamber, a memory anode located at the upper portion of a cell above the memory cathode, and a trigger electrode located at the lower end of a cell beneath the memory cathode, each memory anode electrode being connected to a glow cathode electrode and spaced farther from its associated memory cathode than the associated memory trigger electrode.

5. The tube definedin claim 1 and including an insulating housing for said memory cells, each cell being formed in a separate generally cylindrical chamber in said housing,

each chamber including a relatively large-diameter central region and smaller-diameter upper and lower regions,

the memory cells being vertically oriented beneath said glow cathode electrodes,

each memory cell including a memory cathode located in the central region of a chamber, a memory anode located in the upper region of a chamber above the memory cathode, and a trigger electrode located in the lower region of a chamber beneath the memory cathode, each memory anode electrode being connected to a glow cathode electrode and spaced farther from its associated memory cathode than the associated memory trigger electrode.

6. A cold cathode gaseous glow tube comprising a gas-filled envelope,

an anode electrode and a plurality of glow cathode electrodes mounted in operative relation with each other at the upper portion of said envelope,

and a separate gas-filled memory cell coupled to each glow cathode electrode and positioned at the lower portion of said envelope,

each memory cell including a memory cathode, a me ory anode, and a trigger electrode, each memory anode electrode of a memory cell being connected to a glow cathode electrode.

No references cited.

JAMES W. LAWRENCE, Primary Examiner. S. A. SCHNEEBERGER, Assistant Examiner. 

1. A COLD CATHODE GASEOUS GLOW TUBE COMPRISING A GAS-FILLED ENVELOPE, AN ANODE ELECTRODE, A PLURALITY OF GLOW CATHODE ELECTRODES WITHIN SAID ENVELOPE IN OPERATIVE RELATION WITH SAID ANODE, AND A MULTIPLE ELECTRODE GAS-FILLED MEMORY CELL COUPLED TO EACH GLOW CATHODE ELECTRODE INSIDE SAID ENVELOPE. 